When using a communication device incorporating both the wireless voice communication means and the wireless data communication means, a user needs to select, depending on needs of the user, one of the communication means manually.
Conventionally, switching techniques have been invented for this purpose. For example, Japanese Laid-Open Patent Application No. 72855/1992 (Tokukaihei 4-72855) discloses a switching technique between a telephone and a modem: Japanese Laid-Open Patent Application No. 14583/1993 (Tokukaihei 5-14583) discloses a switching technique between a telephone and a facsimile: Japanese Laid-Open Patent Application No. 223651/1992 (Tokukaihei 4-223651) discloses a switching technique between a facsimile and an answering machine. Nevertheless, these patents concerns one telephone line, and therefore only deals with a switching on the same communication channel. By contrast, the present invention deals with a switching with respect to a plurality of communication means and channels.
When a sending party and a receiving party are to communicate with each other, the two parties need to select the same communication means. Here occurs a trouble: If the user and the opposite party have selected different communication means from each other, the opposite party needs to manually switch to the communication means selected by the user in order to communicate with the user.
Moreover, even when the receiving party is to manually switch to the same communication means with that of the sending party, the receiving party still needs to know in advance which means the sending party is going to use. Besides, the receiving party needs to inform the sending party when the communication will be possible.
Private companies have already put in service, systems which enable communication devices to be switched by the wireless data communication means from the wireless data communication means to the wireless voice communication means. But the availability of the systems totally depends on the companies.
The present invention resolves the above-noted problem that the sending and receiving parties need to select the same communication system in order to communicate with each other, and that the two parties cannot communicate with each other if the communication system selected by the user is different from that of the opposite party. With this technique, even when the communication system does not provide the switching between the communication means, the communication devices can still switch the communication means only by communication between the communication devices.
Additionally, the present invention provides the user with a convenient function of permitting or not permitting the switching between the communication means with respect to time and/or the opposite party.
In view of the trouble that when voice communication is to be performed with a receiving party having a communication device incorporating the two means (namely, the wireless voice communication means and the wireless data communication means), the sending and receiving parties need to select the same wireless communication means, a first problem is how the two parties far away from each other select the same communication means.
A second problem is that if the portable wireless device of a transmitting side has both the wireless voice communication means and the wireless data communication means, and the same communication means is to be selected, the transmitting side needs to switch to the wireless voice communication means, as well as to request the receiving side to switch to the wireless voice communication means.
A third problem is that since the receiving side is not always in a state capable of performing the voice communication in response to a request from the sending side for the switching to the wireless voice communication means, it is necessary to inform the sending side whether or not the receiving side can perform the voice communication.
A fourth problem is that since the receiving side may want to talk only with some specific people, the receiving side needs to decide, depending on the opposite party on the transmitting side, whether the receiving side switches in response to a switching request from the sending side.
A fifth problem is that when a switching request rejection notice is sent back to the opposite party, the opposite party may want to know when the voice communication will be possible, or why the switching is impossible. For these reasons, the present invention realizes such functions by including a message in the sent-back switching request rejection signal.
A sixth problem is that the receiving party of the switching request signal, although not available for voice communication, still wants a third party to answer the call in place of the receiving party. For this reason, the present invention includes a function enabling the transmitting party of the switching request signal to talk with the third party.